Surface Local Structure Determination of Ni(11O)-S Adsorption System by Surface Extended X-Ray Absorption Fine Structure (EXAFS)

Abstract

The local adsorption structure of S on a Ni(110) crystal surface is studied by the polarization-dependent surface EXAFS (extended X-ray absorption fine structure) method. The polarized S K-edge absorption spectra (2400-2900 eV) have been obtained by monitoring S K-LL Auger electron yield and by changing both polar and azimuthal angles of the incident synchrotron radiation. The results of the EXAFS data analysis show that the adsorbate S atom is on the hollow site of the Ni(110) surface and that the first and seco nd nearest neighbor Ni atoms are 2.19 and 2.31Å distant from the S atoms, respectively. This means that the first interlayer spacing in the Ni(110) surface is 10% larger than the spacing in the bulk.